Process for selective adsorption and recovery of lithium from natural and synthetic brines

ABSTRACT

This invention relates generally to a process for selective adsorption and recovery of lithium from natural and synthetic brines, and more particular to a process for recovering lithium from a natural or synthetic brine solution by passing the brine solution through a lithium selective adsorbent in a continuous countercurrent adsorption and desorption circuit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/671,489 filed on May 15, 2018. This application isalso a continuation-in-part of U.S. Patent Application No. 16/010,286filed on Jun. 15, 2018, which claims the benefit of U.S. ProvisionalPatent Application No. 62/520,024 filed on Jun. 15, 2017 and the benefitof U.S. Provisional Patent Application No. 62/671,489 filed on May 15,2018. This application incorporates each of the foregoing applicationsby reference into this document as if fully set out at this point.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates generally to a process for selective adsorptionand recovery of lithium from natural and synthetic brines, and moreparticular to a process for recovering lithium from a natural orsynthetic brine solution by contacting the brine solution with a lithiumselective adsorbent using a continuous countercurrent adsorption anddesorption (“CCAD”) process.

2. Description of the Related Art

Seawater contains about 0.17 mg/kg, and subsurface brines may contain upto 4,000 mg/kg, more than four orders of magnitude greater than seawater. Typical commercial lithium concentrations are between 200 and1,400 mg/kg. In 2015, subsurface brines yielded about half of theworld's lithium production.

The Salton Sea Known Geothermal Resource Area (“SSKGRA”) has the mostgeothermal capacity potential in the United States. Geothermal energy,the harnessing of heat radiating from the beneath the Earth's crust, isa renewable resource that is capable of cost-effectively generatinglarge amounts of power. In addition, the SSKGRA has the potential tobecome North America's prime sources of alkali metals, alkaline earthmetals and transition metals, such as lithium, potassium, rubidium,iron, zinc and manganese.

Brines from the Salton Sea Known Geothermal Resource Area are unusuallyhot (up to at least 390° C. at 2 km depth), hypersaline (up to 26 wt.%), and metalliferous (iron (Fe), zinc (Zn), lead (Pb), copper (Cu)).The brines are primarily sodium (Na), potassium (K), calcium (Ca)chlorides with up to 25 percent of total dissolved solids. While thechemistry and high temperature of the Salton Sea brines have led to theprincipal challenges to the development of the SSKGA, lithium and otherbrine elements typically maintain high commodity value and are used in arange of industrial and technological applications.

The “lithium triangle” of Chile, Argentina and Bolivia is whereapproximately 75% of the world's lithium comes from. Chile is currentlythe second largest producer of lithium carbonate and lithium hydroxide,which are key raw materials for producing lithium-ion batteries, behindonly Australia. Salar de Atacama is one of the hottest, driest, windiestand most inhospitable places on Earth, and the largest operations are inthe shallow brine beneath the Salar de Atacama dry lakebed in Chile,which as of 2015, yielded about a third of the world's supply. TheAtacama in Chile is ideal for lithium mining because thelithium-containing brine ponds evaporate quickly, and the solution isconcentrated into high-grade lithium products like lithium carbonate andlithium hydroxide. Mining lithium in the salars of Chile and Argentinais much more cost-effective than hard rock mining where the lithium isblasted from granite pegamite orebodies containing spodumene, apatite,lepidolite, tourmaline and amblygonite. The shallow brine beneath theSalar de Uyuni in Bolivia is thought to contain the world's largestlithium deposit, often estimated to be half or more of the world'sresource; however, as of 2015, no commercial extraction has taken place,other than a pilot plant. The mining of lithium from brine resources inthe “lithium triangle” historically depends upon easy access to largeamounts of fresh water and very high evaporation rates. With decliningavailability of fresh water and climate change, the economic advantageof conventional processing techniques is disappearing.

Fixed-bed and continuous countercurrent ion exchange (“CCIX”) systemshave been used to recover metals, such as nickel (Ni) and cobalt (Co),from ore leach solutions. While fixed-bed systems are generally used inrecovery projects, they are known to require relatively large amounts ofwater and chemicals and the performance is generally weaker than CCIXsystems.

Utilizing CCIX-type equipment in the adsorption of lithium from brineswith lithium selective adsorbents in a CCAD circuit will bring increasedprocess efficiency versus classical fixed-bed processing. The water andreagent efficiency of a CCAD circuit/process should be a preferredreplacement for evaporation ponds in the brine mining operations in thesalars of “lithium triangle”, saving millions of acre feet of water fromevaporative loss.

It is therefore desirable to provide an improved process for selectiveadsorption and recovery of lithium from natural and synthetic brines.

It is further desirable to provide a continuous countercurrentadsorption and desorption process for the selective recovery of lithiumfrom natural and/or synthetic brines, which are normally consideredeconomically non-viable using conventional membranes, solventextraction, or fixed-bed arrangements of lithium selective adsorbenttechnologies.

It is still further desirable to provide a process for recoveringlithium from a natural or synthetic brine solution by treating the brinesolution with a lithium selective adsorbent in a CCIX-type system usinga CCAD process.

Before proceeding to a detailed description of the invention, however,it should be noted and remembered that the description of the inventionwhich follows, together with the accompanying drawings, should not beconstrued as limiting the invention to the examples (or embodiments)shown and described. Those skilled in the art to which the inventionpertains will be able to devise other forms of this invention within theambit of the appended claims.

SUMMARY OF THE INVENTION

In general, in a first aspect, the invention relates to a process forselective recovery of lithium from a feed brine solution. The processincludes concentrating the lithium in the brine solution by cyclicallyand sequentially flowing the brine solution through a continuouscountercurrent adsorption and desorption circuit to form an enhancedlithium product stream, and recovering the lithium from the enhancedlithium product stream.

The process can also include the steps of removing impurities from thebrine solution to form a polished brine solution, and then concentratingthe lithium in the polished brine solution by cyclically andsequentially flowing the polished brine solution through a continuouscountercurrent adsorption and desorption circuit to form an enhancedlithium product stream. Lithium is then recovered from the enhancedlithium product stream.

The process can also include the step of obtaining the brine solutionhaving lithium chloride. The lithium chloride in the brine solution canbe concentrated using the continuous countercurrent adsorption anddesorption circuit to form the enhanced lithium product stream, andthen, the lithium chloride can be selectively converted to lithiumcarbonate, lithium hydroxide, or both.

The continuous countercurrent adsorption desorption circuit can have aplurality of process zones, with each of the process zones having anadsorbent bed or column containing a lithium selective adsorbent. Thelithium selective absorbent can be a lithium alumina intercalateprepared from hydrated alumina, a lithium aluminum layered doublehydroxide chloride, a layered double hydroxide modified activatedalumina, a layered double hydroxide imbibed ion exchange resin orcopolymer or molecular sieve or zeolite, layered aluminate polymerblends, a lithium manganese oxide, a titanium oxide, an immobilizedcrown ether, or a combination thereof. The process zones can include abrine displacement zone positioned upstream with respect to fluid flowof a brine loading zone, which is positioned upstream with respect tothe fluid flow of and in fluid communication with an entrainmentrejection zone, which is positioned upstream with respect to fluid flowof and in fluid communication with an elution zone, which is in fluidcommunication with the brine displacement zone. The brine solution ispassed through the loading zone for a predetermined amount of contacttime.

The process can also include dewatering the enhanced lithium productstream using a membrane separation, such as reverse osmosis ornano-filtration, in order to produce a high lithium concentration,enhanced lithium product stream and a recycle eluant solution. Theenhanced lithium product stream, the high lithium concentration,enhanced lithium product stream or both can then be passed or providedto a lithium solvent extraction and electrowinning process, a solventextraction and membrane electrolysis process, or a recovery process forproduction of high purity lithium hydroxide and lithium carbonate forbattery production.

The brine solution can be a natural brine, a synthetic brine, or acombination thereof, such as a continental brine, a geothermal brine, anoil field brine, a brine from hard rock lithium mining, or a combinationthereof.

In general, in a second aspect, the invention relates to a continuouscountercurrent adsorption desorption circuit configured for theselective adsorption and recovery of lithium from a lithium-rich brinesolution. The circuit has a plurality of process zones, with each of theprocess zones comprising a plurality of adsorbent beds or columns havinga lithium selective adsorbent. The process zones include a brinedisplacement zone positioned upstream with respect to fluid flow of abrine loading zone, which is positioned upstream with respect to thefluid flow of and in fluid communication with an entrainment rejectionzone. The entrainment rejection zone is positioned upstream with respectto fluid flow of and in fluid communication with an elution zone, andthe elution zone in fluid communication with the brine displacementzone.

The lithium-rich brine solution can be a natural brine, a syntheticbrine, or a combination thereof, such as a continental brine, ageothermal brine, an oil field brine, a brine from hard rock lithiummining, or a combination thereof. The lithium selective absorbent may bea lithium alumina intercalate prepared from hydrated alumina, a lithiumaluminum layered double hydroxide chloride, a layered double hydroxidemodified activated alumina, a layered double hydroxide imbibed ionexchange resin or copolymer or molecular sieve or zeolite, layeredaluminate polymer blends, a lithium manganese oxide, a titanium oxide,an immobilized crown ether, or a combination thereof.

In general, in a third aspect, the invention relates to a continuousadsorption and desorption process for recovery of lithium from a brinesolution. The process includes the steps of:

-   -   a) displacing a lithium-containing feed brine solution from a        freshly loaded adsorbent bed or column using a lithium product        eluate and passing a displacement liquor solution to a brine        feed inlet of a lithium adsorption zone;    -   b) incorporating the displacement liquor solution into the feed        brine solution to form a combined liquor/feed brine solution;    -   c) passing the combined liquor/feed brine solution through a        lithium loading zone where lithium is adsorbed on one or more        loading adsorbent beds or columns and forming a lithium depleted        brine raffinate;    -   d) displacing an eluate solution from the loading adsorbent beds        with a portion of the lithium depleted brine raffinate from the        lithium loading zone and into an elution zone;    -   e) flowing a fresh eluant solution through the elution zone        stripping a portion of lithium adsorbed on the adsorbent beds or        columns; and    -   f) collecting a portion of the eluant having high lithium        concentration as an enhanced lithium product solution.

In fourth aspect, the invention relates to a continuous adsorption anddesorption process for recovery of lithium from a feed brine solution.An eluant solution passes through an elution zone and strips most of thelithium from the lithium loaded adsorbent. A portion of the lithiumproduct solution is captured as the purified lithium concentrate, and asecond portion is employed to displace latent brine from freshly loadedadsorbent. A portion of the lithium product solution along with thedisplaced brine is routed to the brine feed inlet and this recirculationof lithium via the displacement stream increases the effective lithiumconcentration in the brine feed stream. The brine feed solution, alongwith the recycled product and displaced brine, passes through aplurality of adsorbent beds containing lithium selective adsorbent suchthat lithium is selectively loaded onto the adsorbent and produces alithium-depleted brine raffinate. A portion of the lithium-depletedbrine raffinate is introduced to the elution zone, displacing latenteluant solution so it is not lost to raffinate when the first adsorbentbed in the elution zone eventually transitions from the elution zone tothe loading zone. In addition, the process can include membranedewatering of the lithium product eluate to concentrate the productlithium and replenish the low concentration lithium eluant solution.

The foregoing has outlined in broad terms some of the more importantfeatures of the invention disclosed herein so that the detaileddescription that follows may be more clearly understood, and so that thecontribution of the instant inventors to the art may be betterappreciated. The instant invention is not to be limited in itsapplication to the details of the construction and to the arrangementsof the components set forth in the following description or illustratedin the drawings. Rather, the invention is capable of other embodimentsand of being practiced and carried out in various other ways notspecifically enumerated herein. Finally, it should be understood thatthe phraseology and terminology employed herein are for the purpose ofdescription and should not be regarded as limiting, unless thespecification specifically so limits the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further aspects of the invention are described in detail inthe following examples and accompanying drawings.

FIG. 1 is a process diagram of an example of a known crystallizerreactor clarifier process for power plant operations in the Salton SeaKnown Geothermal Resource Area;

FIG. 2 is a flow chart of an example of a process for recovery oflithium carbonate in accordance with an illustrative embodiment of theinvention disclosed herein;

FIG. 3 is a flow chart of an example of a process for recovery oflithium hydroxide in accordance with an illustrative embodiment of theinvention disclosed herein;

FIG. 4A is a process flow diagram of a system and process for recoveryof select minerals and lithium in accordance with an illustrativeembodiment of the invention disclosed herein;

FIG. 4B is a continuation of the process flow diagram shown in FIG. 4A;

FIG. 5 is a flow chart diagram of an example of a CCAD lithium recoveryunit in accordance with an illustrative embodiment of the inventiondisclosed herein;

FIG. 6 is a flow chart of an example of zinc and manganese solventextraction circuit in accordance with an illustrative embodiment of theinvention disclosed herein; and

FIG. 7 is a graphical representation illustrating lithium and calciumconcentrations taken at an underflow of each adsorption column of a CCADlithium recovery unit under a standing-wave steady state operatingcondition in accordance with an illustrative embodiment of the inventiondisclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings, and will herein be describedhereinafter in detail, some specific embodiments of the instantinvention. It should be understood, however, that the present disclosureis to be considered an exemplification of the principles of theinvention and is not intended to limit the invention to the specificembodiments so described.

This invention relates generally to a process for selective adsorptionand recovery of lithium from natural and synthetic brines using CCAD.While the invention is particularly suited for geothermal brines, thesource of the feed brine is not so limited. The feed brine source can befrom any lithium brine deposit, such as continental sources, geothermalsources, oil field sources, or brine from hard rock lithium miningactivity. The feed brine may be subject to a variety of preliminarytreatment steps including the removal of solids and certain problemmetals or metals of commerce (e.g., iron, manganese, zinc, silicon,etc.). Just prior to treatment by the inventive process, the feed brinepreferably has a pH between about 5.0 and about 7.0. The feed brinegenerally includes large quantities of chloride salts of sodium,potassium, and calcium. Higher temperature brines (about 50° C. to about100° C.) improve the kinetic response of the lithium selectiveadsorbent; however, lower temperature brines can also be successfullytreated (about 5° C. to about 50° C.) using the inventive process.

As generally illustrated in FIG. 1, existing power plant operations 1000generally involve a liquid brine flow from geothermal production wells1012 that is partially flashed into steam due to pressure losses as theliquid brine makes its way up the production well casing. The two-phasemixture of brine and steam is routed to a high-pressure separator 1014where the liquid brine and high pressure steam are separated. Highpressure steam 1016 is routed from the separator 1014 to a centrifugaltype steam scrubber (not shown) that removes brine carryover from thesteam, and from there the scrubbed high pressure steam 1016 is routed tothe turbine generator 1020. The liquid brine from the high-pressureseparator 1014 is flashed into a standard-pressure crystallizer 1022,and the standard pressure steam 1024 from the standard-pressurecrystallizer 1022 is passed through a steam scrubber (not shown) andthen the scrubbed standard pressure steam 1024 is routed to the turbine1020. Precipitated solids from the clarifiers are mixed with the brinein the standard-pressure crystallizer 1022 and contact with the scalingmaterials, which reduces the scaling tendency in brine significantly.

A brine slurry mixture from the standard-pressure crystallizer 1022 isflashed into a low-pressure crystallizer 1018. Low pressure steam 1025from the low-pressure crystallizer 1018 flows through a steam scrubber(not shown) and then either to a low-pressure turbine or to thelow-pressure side of a dual entry turbine 1020. The brine slurry mixtureis flashed to atmospheric pressure in an atmospheric flash tank 1026 andthen flows into the clarifiers.

A primary clarifier 1028 comprising an internally recirculating reactortype clarifier precipitates silica down to close to equilibrium valuesfor the various scaling constituents at the operating temperature of thebrine, e.g., approximately 229° F. Primary Clarifier Overflow (“PCO”)refers to the clarified brine flowing out of the primary clarifier 1028,and Primary Clarifier Underflow (“PCU”) refers to the slurry flowing outof the bottom of the primary clarifier 1028. The precipitated solids areflocculated and settled to the bottom of the primary clarifier tank1028. A relatively clear brine PCO passes from the primary clarifier1028 to a secondary clarifier 1030 that removes additional suspendedsolids from the brine. Secondary Clarifier Overflow (“SCO”) 1038 refersto the clarified brine flowing out of the secondary clarifier 1030, andSecondary Clarifier Underflow (“SCU”) refers to the slurry flowing outof the bottom of the secondary clarifier 1030.

Flocculent and scale inhibitor are added between the primary clarifier1028 and the secondary clarifier 1030 to enhance solids settling and toprevent the precipitation of radioactive alkaline earth salts. Thestable SCO 1038 from the secondary clarifier 1030 is pumped intoinjection wells 1032. A portion of the precipitated solids from the PCUand the SCU is recycled upstream to the standard-pressure crystallizer1022 as seed material 1034. Accumulated solids in both the primaryclarifier 1028 and the secondary clarifier 1030 are routed to ahorizontal belt filter (“HBF”) 1036 for solids removal.

The HBF 1036 separates liquid from the solids in the slurry from the PCUand the SCU. The liquid can be separated from the solids by vacuum andpasses through a filter cloth that rests on top of the carrier belt. Thefirst stage of the HBF is a pH 1.0 acid wash of the slurry withhydrochloric acid to remove any lead precipitates from the filter cake.The second stage is a pH 9.5 condensate water wash to neutralize anyresidual acid in the filter cake. The third stage of the HBF steam driesthe filter cake. The filter cake is transported to a local landfill fordisposal.

The silica and iron concentrations in the brine at the PCO, SCO andinjection wells of the power plant operations are summarized as followsin Table 1:

TABLE 1 Si as SiO₂ Fe As K Zn Mn Li Location (mg/kg) (mg/kg) (mg/kg)(mg/kg) (mg/kg) (mg/kg) (mg/kg) PCO 167 ± 25 1,579 ± 123 17.0 ± 4.020,600 ± 2,200 625 ± 42 1,705 ± 101 264 ± 24 SCO 159 ± 19 1,560 ± 88 16.9 ± 4.0 20,600 ± 2,600 639 ± 41 1,693 ± 134 265 ± 23 Injection 160 ±19 1,557 ± 87  16.9 ± 4.0 20,400 ± 2,500 621 ± 45 1,696 ± 92  265 ± 22Wells

The polished brine 1038 that exits the SCO from the power plant 1000with reduced amounts of scaling constituents is well suited for mineralextraction, and rather than injecting the polished brine 1038 into theinjection well 1032, it is made available to the system and process 200and/or to the CCAD process 400 for selective recovery of lithium and/orother minerals from the polished brine 1038.

Recovery of Lithium Carbonate:

As illustrated in FIG. 2, a feed brine, such as a geothermal brine orthe brine 1038 that exits the SCO from the power plant 1000 havingreduced amounts of scaling constituents passes to the system and process200 for mineral and/or lithium extraction. The feed brine is passed intothe impurity removal circuit 300 having a first set of reaction tanks302 and a first clarifier 304 to remove iron and silica followed by asecond set of reaction tanks 306 and a second clarifier 308 to removemanganese and zinc primarily. A first or iron/silica precipitation stage300A of the impurity removal circuit 300 includes adding limestone 310Aand injecting air 310B into brine. The air causes the dissolved iron tooxidize and the pH to drop. A low pH solution reduces the rate ofreaction; therefore, limestone is used to neutralize this effect andmaintain the pH around 5.5. The first clarifier 304 is positioneddownstream of the first set of reaction tanks 302 to settle out thesilica and iron in the brine. The precipitated solids are settled to thebottom of the first clarifier tank 304. The first stage 300A of theimpurity removal circuit 300 reduces the iron concentration in the brineoverflow from about 1,600 part per million (ppm) down to less than about5 ppm and reduces the silica concentration in the brine overflow fromabout 60 ppm down to less than about 5 ppm. A relatively clear brineoverflow passes from the first clarifier 304 to a second orzinc/manganese precipitation stage 300B of impurity removal circuit 300.

The second stage 300B of the impurity removal circuit 300 includesadding limestone 312A and/or lime 312B to the brine in the second set ofreaction tanks 306. This causes the brine pH to elevate to around 8. Thesecond clarifier 308 is positioned downstream of the second set ofreaction tanks 306 and allows the metals as oxides and/or hydroxides(primarily zinc and manganese) to settle. During the second stage 300Bof the impurity removal circuit 300, the manganese concentration in thebrine is reduced from about 1700 ppm down to less than about 10 ppm,while zinc concentration is reduced about 600 ppm down to less than 5ppm in the second stage 300B of the impurity removal circuit 300.Accumulated solids in the first clarifier 304 and the second clarifier308 are respectively routed to a pneumapress filter HBF to prepare anFe/Si filter cake 314 and a Mn/Zn filter cake 316.

Acid is then added 318 to the brine from the second clarifier 308 toreduce the pH back down to between about 4.5 and about 6.0, with a brinetemperature between about 5° C. and about 100° C., which is suitable forthe CCAD circuit 400. The dissolved solids in the polished brine at thispoint in the process comprise primarily salts (as chlorides) with highconcentrations of sodium, potassium, and calcium. The lithiumconcentration is comparatively low at only ±250 ppm.

The polished brine (stream 54 in FIG. 4A) can then passed to the CCADcircuit 400, which concentrates the lithium in the polished brine byapproximately 10 times and simultaneously separates the lithium from theother salts (calcium is of particular concern for downstreamoperations). The target result is an enhanced lithium chloride productstream 342 in FIGS. 2 and 3 (stream 57 in FIG. 4A) (stream 417 or stream420 in FIG. 5) (with some residual impurities) of around approximately2,500 to 3,000 ppm lithium. The residual brine can be returned forreinjection through injection wells 320.

If the inventive CCAD system is used with salar, continental or othernon-geothermal brines, the brine feedstock can be passed directly to theCCAD circuit 400 with minimal pretreatment such as granular mediafiltration (GMF) and, if necessary, residual organic removal. Salar orcontinental brines with low iron and silica content may require onlyminimal pretreatment before being passed to the CCAD circuit 400 forconcentrating lithium when compared to brines from the Salton Sea KnownGeothermal Resource Area (SSKGRA). The pretreatment process may includedilution with water to prevent solids precipitating from brines that areclose to saturation. In addition, GMF can be used to reduce totalsuspended solids (TSS) to below 10 ppm before introducing the brinesolution. Oil field brines may require pretreatment processing to removeany residual organic material before being passed to the CCAD circuit400. The bulk of the organic material can be removed by a device such asan API oil-water separator. Any remaining organic materials can beremoved with a mixed bed GMF that includes activated carbon as part ofthe mixed bed.

Referring now to FIG. 5, the CCAD circuit 400 includes a series ofsequential steps in a cyclic process. The CCAD circuit 400 has aplurality of adsorption beds or columns 402 each containing a lithiumselective adsorbent. The adsorption beds 402 are sequentially subjectedto individual process zones (A, B, C, D) as part of the CCAD circuit400. Each of the process zones A, B, C, and D includes one or more ofthe adsorbent beds 402 configured in parallel, in series, or incombinations of parallel and series, flowing either in up flow or downflow modes. The process zones of the CCAD circuit 400 include anadsorption displacement zone A, an adsorption loading zone B, anentrainment rejection (ER) zone C, and an elution zone D. Brine fluidflow through the CCAD circuit 400 is controlled by pumping flow ratesand/or predetermined indexing of a central multi-port valve system or ofthe adsorbent beds 402, creating a process where the adsorption beds 402continually cycle through the individual process zones A, B, C and D.

In order to eliminate the possibility of residual feedstock brine 413and brine salts from entering the elution zone D, an elution volume offeed brine 412 is displaced from the adsorbent bed(s) 402 of the brinedisplacement zone A using a portion of high lithium concentrationproduct eluate 411 from the elution zone D. The elution volume ofdisplacement feed brine 412 drawn from the elution zone D into the brinedisplacement zone A is at least enough to displace one adsorbent bedvoid fraction during an index time (the time interval between rotaryvalve indexes).

The feedstock brine 413, which can be the polished geothermal brine(stream 54 in FIG. 4A) or a salar, continental or other non-geothermalfeedstock brine, is pumped to the adsorbent bed(s) 402 in the loadingzone B with a predetermined elution time sufficient to completely oralmost completely exhaust the lithium selective adsorbent, and thedepleted brine exiting the loading zone B is sent to raffinate 414. Theloading zone B is sized such that under steady state operation of theCCAD circuit 400, the complete lithium adsorption mass transfer zone iscaptured within the zone B. The steady state operation treats thefeedstock brine 413 so that the maximum lithium loading is achievedwithout significant lithium leaving with the lithium depleted raffinate414 as tails.

Next, a portion of raffinate 414A is pumped to the entrainment rejection(ER) zone C to displace latent eluate solution 415, which is carriedforward as entrained fluid within the column transitioning from theloading zone C into the elution zone D in the cyclic process, back tothe inlet of the elution zone D. The elution volume of the displacementfluid 414A drawn from the raffinate 414 to displace latent eluatesolution 415 back into the ER zone C is at least enough to displace oneadsorbent bed void fraction during the rotary valve index time.

Then, an eluant (stripping solution) 416 is pumped countercurrent to theadsorbent advance (fluid flow is illustrated as right to left, while theadsorbent beds movement is illustrated as left to right) into theelution zone D to produce an enhanced lithium product stream 417. Eluant416 comprises a low concentration lithium product eluant (as neutralsalts, generally lithium chloride) in water at a concentration fromabout 0 mg/kg to about 1000 mg/kg lithium and at temperatures of about5° C. to about 100° C. Properly tuned, the enhanced lithium productstream 417 will have a lithium concentration 10- to 20-fold that of theeluant 416 and greater than 99.8% rejection of brine hardness ions andmost other brine components. The portion of high lithium concentrationproduct eluate 411 that is recycled and displaces the displacement feedbrine 412 from the displacement zone A is enough fluid to completelydisplace brine salts from the adsorbent before the adsorbent enters theelution zone D. This means that the displacement feed brine 412 may berecycled introduced to the loading zone B with the feedstock brine 413.Depending on the tuning parameters of the CCAD circuit 400, the lowlithium concentration in the recycled displacement feed brine 412 couldsignificantly increase the effective concentration of lithium enteringthe loading zone B. This enhanced feed concentration results insignificantly increased lithium capacity and greater lithium recoveryefficiency, especially in the case of feedstock brines with low lithiumconcentrations (under 200 mg/kg).

An optional membrane separation 418 can be inserted into stream 417,which includes but is not limited to, reverse osmosis ornano-filtration, to dewater and concentrate the lithium product solution417 producing a product eluate with higher lithium concentration 420,while producing a recycle stream 419 suitable for use as make-up forfresh eluant 416. The optional membrane dewatering of the enhancedlithium product stream 417 would recycle a portion of the water 419 usedin the preparation of the eluant solution 416. Depending on thepermeability of the membrane, a portion of the lithium could passthrough the membrane without passing multivalent brine components andbecome the lithium make-up for fresh eluant 416.

The CCAD circuit 400 recovers between about 90% and about 97% of thelithium from the feed brine and produces the enhanced lithium chlorideproduct stream 342 in FIGS. 2 and 3 (stream 57 in FIG. 4A) (stream 417or stream 420 in FIG. 5) having a concentration 10-to 50-fold that ofthe feed brine (e.g., polished brine stream 54 in FIG. 4A or othernatural or synthetic brine feedstock) with a greater than 99.9%rejection of brine hardness ions. The production of this high puritylithium, directly from brine, without the need for extra rinse water, isan extremely cost-effective process of obtaining commercially valuableand substantially pure lithium chloride, suitable for conversion tobattery grade carbonate or hydroxide.

The lithium selective adsorbent in the adsorbent beds 402 can be lithiumalumina intercalates prepared from hydrated alumina, lithium aluminumlayered double hydroxide chloride (LDH), LDH modified activated alumina,LDH imbibed ion exchange resins or copolymers or molecular sieves orzeolites, layered aluminate polymer blends, lithium manganese oxides(LMO), titanium oxides, immobilized crown ethers, or other lithium ionselective binding material.

The process for selective adsorption and recovery of lithium fromnatural and synthetic brines disclosed herein is further illustrated bythe following examples, which are provided for the purpose ofdemonstration rather than limitation.

An exemplary CCAD circuit 400 was configured in general accordance withFIG. 5 using thirty (30) individual adsorption columns 402 arranged in arotating carrousel pilot skid with a central rotary valve design witheach column having a 1.0 inch inner diameter and 35 inches in length,each packed with 355 mL of macroporous resin imbibed with lithiumalumina intercalate. All metal analysis was performed using inductivelycoupled plasma (ICP) analysis. The adsorbent bed advance rate was set to4.33 minutes per forward step of the rotating carrousel. The turret ofadsorption columns was maintained in an enclosure at 70-80° C. All feedsolutions were introduced to the circuit at 85° C. The brinedisplacement zone (zone A) comprised four (4) columns in series and theflow rate was set at 80 mL/min. The adsorption zone (zone B) comprisedsix (6) sets of three (3) parallel columns arranged in series. The feedbrine comprised a treated Salton Sea geothermal brine at pH 5.6 wherethe silica, iron, manganese, and zinc had been selectively removed in apretreatment protocol and the brine flow rate was set at 660 mL/min,specific gravity 1.18. Next the ER zone (zone C) comprised two (2)columns in series and the lithium depleted brine raffinate entered theER zone at a flow rate of 50 mL/min. The elution zone (zone D) comprisedthree (3) pairs of parallel columns arranged in series and was fed by 80mL/min of low concentration lithium (300 mg/L) in water as eluate. Theproduct lithium was taken from the last of the three (3) pairs ofparallel columns at a flow rate of 53 mL/min and the remainder of theflow entered zone A to displace brine to the brine feed port at the flowrate of 80 mL/min (as stated above).

The CCAD circuit 400, after achieving steady state operation, providedexcellent results for lithium recovery. The feed brine had an averagelithium concentration of 216 mg/L while the lithium product stream hadan average lithium concentration of 2,500 mg/L, and as such, in thisexample, greater than 93% of the lithium from the feed brine wasrecovered.

In addition, the inventive process provides excellent results for thepreparation of a lithium chloride product having low calcium andmagnesium concentrations, which is particularly suited as a feedstockfor a solvent extraction and electrowinning (SX/EW) process, a solventextraction and membrane electrolysis (SX/EL) process, or other recoverytechnology process for production of high purity lithium hydroxide andlithium carbonate for battery production. The feed brine contained27,880 mg/L of calcium yet the lithium product stream contained only 300mg/L of calcium, representing a 99.98% rejection of calcium from thefeed brine to the lithium product stream.

Another exemplary CCAD circuit 400 was configured in general accordancewith FIG. 5 using thirty (30) individual adsorption columns arranged ina rotating carrousel pilot skid with a central rotary valve design witheach column having a 2.0 inch inner diameter and 48 inches in length,each packed with 2.8 L of macroporous resin imbibed with lithium aluminaintercalate. All metal analysis was performed using ICP analysis. Theadsorbent bed advance rate was set to 6.00 minutes per forward step ofthe rotating carrousel. The turret of columns was maintained in anenclosure at about 40° C. All feed solutions were introduced to thesystem at 77° C. The brine displacement zone A comprised four (4)columns in series and the flow rate was set at 340 mL/min. Theadsorption zone B comprised six (6) sets of three (3) parallel columnsarranged in series. The feed brine comprised treated Salton Seageothermal brine at pH 5.6 where the silica, iron, manganese, and zinchad been removed in a pretreatment protocol and the brine flow rate wasset at 3,050 mL/min, specific gravity 1.18. Next the ER zone C comprisedtwo (2) columns in series and the lithium depleted brine raffinateentered the ER zone C at a flow rate of 250 mL/min. The elution zone Dcomprised three (3) pairs of parallel columns arranged in series and wasfed by 580 mL/min of low concentration lithium (100 mg/kg) in water aseluate. The product lithium was taken from the last of the three (3)pairs of parallel columns at a flow rate of 240 mL/min and the remainderof the flow entered the zone A to displace brine to the brine feed portat the flow rate of 340 mL/min.

In this example, the CCAD circuit 400, after achieving steady stateoperation, provided excellent results for lithium recovery. The feedbrine had an average lithium concentration of 240 mg/kg while thelithium product stream had an average lithium concentration of 3,270mg/kg, and the average concentration of lithium in the raffinate was 8mg/kg, as such, in this example, lithium recovery was greater than 93%of the lithium from the feed brine. Table 2 below shows the steady stateperformance of the inventive process as exemplified in this example. TheCCAD product stream was 7.9% of the volume of the treated Salton SeaBrine feed stream. Quantities of metals are expressed in mg/kg and arecorrected for differences in specific gravity of feed brine vs CCADproduct.

TABLE 2 CCAD Product Volume = 9.3% of Feed Brine Feed Feed CCAD %Reporting % Rejection Brine Brine Product to CCAD from CCAD Element(mg/kg) (mg/L) (mg/L) Product Product Li 240 283 3,250 93.70% 6.3% Ca43,130 50,893 407 0.09% 99.91% Mg 86.4 102 1.64 0.17% 99.83% Na 64,76076,417 117 0.02% 99.98% K 19,180 22,632 39 0.02% 99.98%

In addition, similar to the first example and as illustrated in FIG. 7,the inventive CCAD circuit 400 provides excellent results for thepreparation of a lithium chloride product having low calcium andmagnesium concentrations, which is particularly suited as a feedstockfor a SX/EW process, a SX/EL process, or other recovery technologyprocess for production of high purity lithium hydroxide and lithiumcarbonate for battery production. The feed brine contained 29,770 mg/kgof calcium yet the lithium product stream contained only 403 mg/kg ofcalcium, representing a 99.98% rejection of calcium from the feed brineto the lithium product stream. Magnesium rejection was similar tocalcium rejection giving indication that the inventive process could bewell suited to salar, continental, petro-, or other non-geothermalfeedstock brines.

The CCAD circuit 400 having only one multi-port valve is far simpler tooperate than classical continuous fixed bed systems having 50-60 valves.In addition to the high lithium yields, the CCAD circuit 400 also usesabsorbent, water, and reagents more efficiently than fixed bed systems.In the above examples, the CCAD circuit 400 requires only about half thevolume absorbent as a comparable classical fixed bed system.

Turn back now to FIG. 2, after leaving the CCAD circuit 400, theenhanced lithium chloride product stream 342 (stream 57 in FIG. 4A)(stream 417 or stream 420 in FIG. 5) is passed to the lithium chlorideconversion circuit 500 where the lithium concentration is furtherincreased to in excess of about 3,000 ppm. The lithium chlorideconversion circuit 500 removes selected remaining impurities and furtherconcentrates lithium in the lithium chloride product stream 342 beforecrystallization or electrolysis.

The lithium chloride conversion circuit 500 initially removes anyremaining impurities 502, namely calcium, magnesium and boron, from thelithium chloride product stream 342. First, sodium hydroxide (causticsoda) is added in order to precipitate calcium and magnesium oxides fromthe lithium chloride product stream 342. The precipitated solids canproduce a Ca/Mg filter cake 504. Boron is then removed by passing thelithium chloride product stream 342 through a boron ion exchange (IX)circuit 528. The boron IX circuit is filled with an adsorbent thatpreferentially attracts boron, and divalent ions (essentially calciumand magnesium) are further removed in a divalent ion exchange (IX)circuit 530. This “polishing” step 502 ensures that these calcium,magnesium and boron contaminants do not end up in the lithium carbonateor lithium hydroxide crystals.

Then, the lithium chloride conversion circuit 500 uses a reverse osmosismembrane step 506 to initially concentrate lithium in the lithiumproduct stream 342 (target estimate from approximately 3,000 ppm to5,000 ppm). A triple effect evaporator 508 is then used to drive offwater content and further concentrate the lithium product stream. Thetriple effect evaporator 508 utilizes steam 510 from geothermaloperations and/or fuel boiler to operate. After processing through theevaporator 508, lithium concentration in the product stream is increasedfrom about 5,000 ppm to about 30,000 ppm.

The next steps in the lithium chloride conversion circuit 500 convertthe lithium chloride in solution to a lithium carbonate crystal. Sodiumcarbonate is added 512 to the lithium chloride product stream 342 toprecipitate lithium carbonate 514. The lithium carbonate 514 slurry issent to a centrifuge 516 to remove any excess moisture resulting inlithium carbonate cake. The lithium carbonate cake is re-dissolved 518,passed through a final purification or impurity removal step 520, andrecrystallized 522 with the addition of carbon dioxide 524. Thecrystallized lithium carbonate product is then suitable for packaging527.

Recovery of Lithium Hydroxide:

FIG. 3 illustrates another exemplary embodiment of the system andprocess 200 for recovery of lithium. After leaving the CCAD circuit 400,rather than using evaporation 508 exemplified in FIG. 2, a solventextraction process 702 concentrates lithium in the enhanced lithiumchloride product stream 342 in FIGS. 2 and 3 (stream 57 in FIG. 4A)(stream 417 or stream 420 in FIG. 5) using liquid-liquid separation, andafter solvent extraction 702 and electrolysis 708, the lithium issubsequently crystallized 710 into lithium hydroxide product 712.

Similar to the embodiment illustrated in FIG. 2, the lithium chlorideconversion circuit 500 first precipitates calcium and magnesium 502through the addition sodium hydroxide (caustic soda) resulting with aCa/Mg filter cake is produced 504. The pH of the lithium chlorideproduct stream 342 is lowered to about 2.5 in step 700 and then theacidified lithium chloride product stream 342 is introduced to thesolvent extraction step 702 in pulsed columns (tall vertical reactionvessels). The flow is scrubbed 704 and then stripped 706 with sulfuricacid producing a lithium sulfate product. The lithium sulfate productgoes through an electrolysis unit 708 producing lithium hydroxidecrystals 710. The lithium hydroxide crystals are then dried and packaged712.

Selective Recovery of Zinc, Manganese and Lithium:

Turning now to FIGS. 4 illustrating yet another exemplary embodiment ofthe process for recovery of lithium, the feed source is an incomingbrine (e.g., a geothermal brine or the polished brine 1038) (stream 1)and dilution water (stream 2). The incoming dilution water (stream 2) ismixed with filtrate (stream 25) from a Fe/Si precipitate filter 322,then split, part (stream 21) being used as wash to the Fe/Si precipitatefilter 322 and the balance (stream 3) being added to the incoming brine(stream 1). The combined brine, dilution water and Fe/Si filtrate(stream 4) is pumped (stream 5) to the Fe/Si precipitation stage 300A ofthe impurity removal circuit 300. Limestone 310A (stream 169) isslurried with recycled barren brine (stream 168). The limestone/recycledbarren brine slurry is added (stream 6) to the first set of reactiontanks 302 along with recycled precipitate seed (stream 18). Air isinjected (stream 7/8) into the first tank 302 using a blower 324. Theiron is oxidized, and iron and silica are precipitated according to thefollowing stoichiometry:

2CaCO₃+2Fe²⁺+3H₂O+½O₂→2Fe(OH)₃+2CO₂+2Ca²⁺

3CaCO₃+3H₄SiO₄+2Fe(OH)₃→Ca₃Fe₂Si₃O₁₂+3CO₂+9H₂O

The spent air is vented (stream 9) from the first tanks 302, and theexit slurry (stream 10) is pumped (stream 11) to a thickener orclarifier 304 where flocculent (stream 12/13) is added and the solidsare settled out. The underflow from the clarifier 304 (stream 15) ispumped (stream 16) back to the first set of reaction tanks 302 as seed(stream 17) and (stream 19) to the filter feed tank 326. Precipitatefrom the Ca/Mg precipitation stage 540 of the impurity removal circuit502 is added (stream 73) and the combined slurry (stream 20) is filteredin the Fe/Si filter 322. The resulting Fe/Si filter cake is washed withdilution water (stream 22) and the washed filter cake 328 (stream 23)leaves the circuit 300. The filtrate (stream 24) is pump (stream 25) tothe dilution water tank 330.

The clarifier overflow (stream 14) from the Fe/Si precipitation stage300A is combined with filtrate from a Zn/Mn precipitate filter 332(stream 45) in a feed tank 338 and the combined solution (stream 26) ispumped (stream 27) to the Zn/Mn precipitation stage 300B. Recycledprecipitate (stream 38) is added as seed and lime 312B (stream 173) isslaked with recycled barren solution (stream 172). Any gas released isvented (stream 174). The lime/recycled barren solution is added (stream28) to the second set of reaction tanks 306 to raise the pH to just over8 and precipitate zinc, manganese and lead oxides/hydroxides.

Any gas released is vented (stream 29) from the second set of reactiontanks 306. The exit slurry (stream 30) is pumped (stream 31) to theclarifier 308. Recycled solids from a subsequent polishing filter 334(stream 47) and flocculent (stream 32/33) are added and the precipitatedhydroxides are settled out. The clarifier underflow (stream 35) ispumped (stream 36) to seed recycle (stream 37) and to the Zn/Mnprecipitate filter 332 (stream 39). The resulting Zn/Mn filter cake iswashed with process water (stream 41) and the washed filter cake 336(stream 43) leaves the circuit 300. The filtrate (stream 44) is pumped(stream 45) to the feed tank 338 ahead of the Zn/Mn precipitation stage300B. The clarifier overflow (stream 34) is mixed with mother liquor(stream 134) from a first precipitation of lithium carbonate 514 and thecombined solution (stream 49) is pumped (stream 50) through thepolishing filter 334 to capture residual solids. The captured solids arebackwashed out (stream 46) and sent to the Zn/Mn precipitate clarifier308.

The filtrate from the polishing filter 334 (stream 51) is mixed withspent eluant from the divalent IX circuit (stream 95) and hydrochloricacid 338 (stream 52/53) is added to reduce the pH to approximately 5.5.The resulting solution is cooled to approximately 185° F. in the mixingtank 340 and the cooled solution (stream 54) is passed through the CCADcircuit 400 in which the lithium chloride is selectively captured ontothe lithium selective adsorbent. The resulting barren solution (stream55) is pumped (stream 48) to a holding tank 343 from which it isdistributed as follows:

to slurry the limestone to the Fe/Si precipitation stage 300A (stream167);

to slake the lime to the Zn/Mn precipitation stage 300B (stream 171);and

the balance (stream 165) is pumped away (stream 166) to be reinjectedinto the injection wells 320.

The loaded adsorbent is eluted with process water (stream 56) and theresulting eluate (stream 57) is pumped (stream 58) to a third set ofreaction tanks 532 for addition impurity removal 502, initially calciumand magnesium precipitation. Sodium hydroxide 554 (stream 179) isdissolved in process water (stream 181) and added (stream 59) to thetanks 532. Sodium carbonate 536 (stream 176) is dissolved in processwater (stream (177) pumped from a process water reservoir 538 and added(stream 60). A bleed of mother liquor (stream 156) from a secondprecipitation of lithium carbonate 524 and the spent regenerant from theboron IX circuit 528 (stream 192) are also treated in the Ca/Mgprecipitation section of the lithium chloride conversion circuit 500.The alkali earth ions (mainly Ca²⁺ and Mg²⁺) are precipitated accordingto the following stoichiometry:

Mg²⁺+2NaOH→2Na⁺+Mg(OH)₂

Ba²⁺+2NaOH→2Na⁺+Ba(OH)₂

Sr²⁺+2NaOH→2Na⁺+Sr(OH)₂

Ca²⁺+Na₂CO₃→2Na⁺+Ca(CO)₃

Any vapor evolved is vented (stream 61). The exit slurry (stream 62) ispumped (stream 63) to a thickener or clarifier 540, flocculent is added(stream 64/65) and the precipitate is settled out. The overflow (stream68) is pumped (stream 69) through a polishing filter 542. The underflow(stream 66) is pumped (stream 67) to a mixing tank 544 where it joinsthe solids (stream 70) from the polishing filter 542 and the combinedslurry (stream 72) is pumped (stream 73) back to the feed tank 326 aheadof the Fe/Si filter 322. The filtrate (stream 71) from the polishingfilter 542 is pumped (stream 74) to a feed tank 546 ahead of the boronIX circuit 528.

The filtrate (stream 75) from the Ca/Mg precipitation section of thelithium chloride conversion circuit 500 is pumped (stream 76) throughthe boron IX circuit 528 in which boron is extracted onto an ionexchange resin. The loaded resin is stripped with dilute hydrochloricacid (stream 78) that is made from concentrated hydrochloric acid(stream 185), process water (stream 186) and recycled eluate (stream80). The first 50% of the spent acid (stream 79), assumed to contain 80%of the boron eluted from the loaded resin, is mixed with similar spentacid from the subsequent divalent IX circuit 530 and recycled to thefeed to the CCAD circuit 400 (stream 94). The balance of the spent acid(stream 80) is recycled to the eluant make-up tank and recycled (stream77). The stripped resin is regenerated with dilute sodium hydroxide(stream 82) that is made from fresh sodium hydroxide (stream 188),process water (stream 189) and recycled regenerant (stream 84). Thefirst 50% of the spent regenerant (stream 83) is recycled to the Ca/Mgprecipitation section and the balance (stream 84) returns to aregenerant make-up tank 548 and is recycled (stream 81).

The boron-free product solution (stream 85) is pumped (stream 86)through divalent IX circuit 530 in which 99 percent of any remainingdivalent ions (essentially only Ca²⁺ and Mg²⁺) are captured by theresin. The loaded resin is stripped with dilute hydrochloric acid(stream 88) that is made from fresh hydrochloric acid (stream 182),process water (stream 184) and recycled spent acid (stream 93). Thefirst 50% of the spent acid (stream 91) joins the first half of thespent acid from the boron IX circuit 528 and the combined solution(stream 94) is sent back to the feed tank 340 ahead of the CCAD circuit400. The balance of the spent acid (stream 93) goes back to an eluantmake-up tank 550 and is recycled (stream 87). The stripped resin isconverted back to the sodium form by regeneration with dilute sodiumhydroxide (stream 89). The first 50% of the spent regenerant (stream92), assumed to have regenerated 80% of the resin, joins the spentregenerant (stream 83) from the boron ion exchange stage and goes back(stream 191) to the Ca/Mg precipitation section. The balance of thespent regenerant (stream 90) returns to the regenerant make-up tank 548.

The purified solution (stream 96) is pumped (stream 97) to a feed tank552 ahead of reverse osmosis 506 and mixed with wash centrate (stream131) from a first lithium carbonate centrifuge 554. The combinedsolution is split, part (stream 162) being used to dissolve sodiumcarbonate and the balance (stream 98) being pumped (stream 99) through areverse osmosis stage in which the water removal is manipulated to give95 percent saturation of lithium carbonate in the concentrate (stream101). The permeate goes to the process water reservoir (stream 100).

The partially concentrated solution from reverse osmosis 506 is furtherconcentrated in a triple-effect evaporation 508. The solution ex reverseosmosis (stream 101) is partly evaporated by heat exchanger 556 withincoming steam (stream 103). The steam condensate (stream 104) goes tothe process water reservoir 538, and the steam/liquid mixture to theheat exchanger 556 (stream 105) is separated in a knock-out vessel 558.The liquid phase (stream 109) passes through a pressure reduction 560(stream 110) and is further evaporated in a heat exchanger 562 withsteam (stream 106) from the first knock-out vessel 558. The condensate(stream 107) is pumped (stream 108) to the process water reservoir 538.The steam-liquid (stream 111) mixture is separated in a second knock-outvessel 564. The liquid (stream 115) goes through another pressurereduction step 566 (stream 116) and is evaporated further another heatexchanger 568 with steam (stream 112) from the second knock-out vessel564. The condensate (stream 113) is pumped (stream 114) to the processwater reservoir 538. The steam-liquid mixture (stream 117) is separatedin a third knock-out vessel 570. The steam (stream 118) is condensed(stream 119) by heat exchanger 572 with cooling water and pumped (stream120) to the process water reservoir 538.

The concentrated solution (stream 121) is pumped (stream 122) to thelithium carbonate crystallization section 514. Sodium carbonate 536(stream 175) is dissolved in dilute lithium solution (stream 163) fromthe feed tank 552 ahead of reverse osmosis 506 and added (stream123/124) to precipitate lithium carbonate. Any vapor evolved is vented(stream 125). The resulting slurry (stream 126) is pumped (stream 127)to a centrifuge in which the solution is removed, leaving a high solidscake. A small amount (stream 129) of process water is used to wash thesolids. The wash centrate (stream 130) is returned to the feed tankahead of reverse osmosis 506. The primary centrate (stream 133) isrecycled to a feed tank 336 ahead of the polishing filter 334 before theCCAD circuit 400.

The washed solids (stream 135) from the first centrifuge 554 are mixedwith wash (stream 136) and primary centrate (stream 153) from a secondcentrifuge 576. The resulting slurry (stream 137) is pumped to 15 barabs. (stream 138) and contacted with pressurized carbon dioxide 526(stream 139) to completely dissolve the lithium carbonate according tothe following stoichiometry:

Li₂CO₃+CO₂+H₂O→2Li⁺+2HCO₃ ⁻

The amount of primary centrate is manipulated to give 95 percentsaturation of lithium carbonate in the solution (stream 141) leaving theredissolution step 518. Any other species (Ca, Mg) remain as undissolvedcarbonates. The temperature of this step is held at 80° F. by heatexchange with chilled water 578 (stream 194 in, stream 193 out). Theresulting solution of lithium bicarbonate (stream 141) is filtered 580and the solid impurities leave the circuit 500 (stream 142). Thefiltrate (stream 143) is heated by live steam (stream 144) injection, todecompose the dissolved lithium bicarbonate to solid lithium carbonateand gaseous carbon dioxide:

2Li⁺+2HCO₃ ⁻→Li₂CO₃↓+CO₂↑+H₂O

The carbon dioxide formed (stream 145) is cooled by chiller 582 (stream157) and mixed with surplus carbon dioxide (stream 140) from there-dissolution step 518 and make-up carbon dioxide 528 (stream 158) in aknock-out vessel 586 from which the condensed water (stream 159) isremoved and the carbon dioxide (stream 160) is compressed 584 andreturned (stream 139) to the lithium re-dissolution step 518. The slurryof purified lithium carbonate (stream 146) is pumped (stream 147) to thesecond centrifuge 576 in which it is separated and washed with processwater (stream 148). The wash centrate (stream 152) is returned to there-dissolution step 518. The primary centrate (stream 150) is pumped(stream 151) back to the Ca/Mg precipitation section (stream 155) and tothe lithium re-dissolution step (stream 136). The washed solids (stream154) leave the circuit as the lithium carbonate product.

The condensate from the carbon dioxide knock-out vessel 586 (stream 159)and condensate from the carbon dioxide compressor 584 (stream 161) arecombined and sent (stream 195) to the process water reservoir 538. Thepermeate from the reverse osmosis 506 (stream 100) and the condensatesfrom the evaporation sequence 508 (streams 104, 108, 14) also go to theprocess water reservoir 538. Make-up water (stream 164) is added to theprocess water reservoir 538, if necessary, to balance the followingrequirements for process water:

wash to the Zn/Mn precipitate filter 332(stream 40);

eluate to the CCAD circuit 400 (stream 149);

centrifuge 554/576 wash water (streams 128/132); and

reagent make-up water (streams 178/181/183/187/190).

Selective Recovery of Zinc and Manganese:

FIG. 6 shows an illustrative example of mineral recovery as part of thesystem and process 200 disclosed herein. After the impurity removalcircuit 300, the recovery of metals from the second filter cake 316 ispossible through a solvent extraction (SX) circuit 600. The SX circuitleaches manganese and zinc from the filter cake with an application ofan acid and then selectively strips the manganese and zinc using asolvent under different pH conditions. The resulting intermediateproducts are zinc sulfate liquor and manganese sulfate liquor, both ofwhich can be sold as agricultural products, processed further byelectrowinning into metallic form, or as feedstock to alternativeproducts such as electrolytic manganese dioxide among others.

The SX circuit 600 begins with leaching 604 the second filter cake 316in a stirred, repulp reactor 602 with sulfuric acid (H₂SO₄) orhydrochloric acid (HCl) to reduce the pH down to about 2.5 (606). Areducing agent such as NaHS or SO₂ is added to the reactor 602 to ensureall of the manganese is in the +2-valence state for leaching. Thisimproves the kinetics and yield of the acid leach. The discharge fromthe leach reactor 602 will have its pH raised to approximately 5-6 withlime to precipitate any residual iron. The slurry will then be pumped toa polishing filter (not shown) followed by a pH adjustment toapproximately 2 to approximately 3. This becomes the Zn/Mn aqueous feedsolution 614 to the SX circuit 600.

The SX circuit 600 includes a zinc extraction stage 608, a zincscrubbing stage 610, and a zinc stripping stage 612. The Zn/Mn aqueousfeed solution 614 and an organic solvent 616 (e.g., Cytex 272) are fedin a counter-current manner into a first stage contactor in which thetwo phases are mixed and Zn is transferred from the aqueous phase intothe organic phase. After settling, the aqueous raffinate is separated618 and pH adjusted to between approximately 4.5 and approximately 5.5.After pH adjustment 620, the raffinate containing Mn 618 is sent forrecovery of a manganese sulfate product liquor 622.

From the zinc extraction stage 608, the zinc loaded solvent 624 is fedinto a second stage contactor where it is scrubbed with a suitableaqueous solution 626 to remove small amounts of impurities remaining.After settling in the zinc scrubbing stage 610, the scrub raffinate willbe recycled to an appropriate stream 628. The loaded solvent 630 is thenpumped to the zinc stripping stage 612 and fed into a third stagecontactor in which the Zn is stripped from the organic phase by asulfuric acid solution. The aqueous concentrated strip ZnSO4 productliquor 632 then goes for further processing depending on the desiredproduct form. The stripped solvent 616 is recycled back to the zincextraction stage 608.

The SX circuit 600 includes a manganese extraction stage 634, amanganese scrubbing stage 636, and a manganese stripping stage 638.Similar to the zinc SX circuit, the raffinate containing Mn 618 and anorganic solvent 648 (e.g., Cytex 272) are fed in a counter-currentmanner into a first stage contactor in which the two phases are mixedand Mn is transferred from the aqueous phase into the organic phase. Themanganese loaded solvent 640 is fed into a second stage contactor whereit is scrubbed with a suitable aqueous solution 642 to remove smallamounts of impurities remaining. After settling in the manganesescrubbing stage 636, the scrub raffinate will be recycled to anappropriate stream 644. The loaded solvent 646 is then pumped to themanganese stripping stage 638 and fed into a third stage contactor inwhich the Mn is stripped from the organic phase by a sulfuric acidsolution. The aqueous concentrated strip MnSO4 product liquor 622 thengoes for further processing depending on the desired product form. Thestripped solvent 648 is recycled back to the manganese extraction stage634.

It is to be understood that the terms “including”, “comprising”,“consisting” and grammatical variants thereof do not preclude theaddition of one or more components, features, steps, or integers orgroups thereof and that the terms are to be construed as specifyingcomponents, features, steps or integers.

If the specification or claims refer to “an additional” element, thatdoes not preclude there being more than one of the additional element.

It is to be understood that where the claims or specification refer to“a” or “an” element, such reference is not be construed that there isonly one of that element.

It is to be understood that where the specification states that acomponent, feature, structure, or characteristic “may”, “might”, “can”or “could” be included, that particular component, feature, structure,or characteristic is not required to be included.

Where applicable, although state diagrams, flow diagrams or both may beused to describe embodiments, the invention is not limited to thosediagrams or to the corresponding descriptions. For example, flow neednot move through each illustrated box or state, or in exactly the sameorder as illustrated and described.

Systems and processes of the instant disclosure may be implemented byperforming or completing manually, automatically, or a combinationthereof, selected steps or tasks.

The term “process” may refer to manners, means, techniques andprocedures for accomplishing a given task including, but not limited to,those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the art to which the invention belongs.

For purposes of the instant disclosure, the term “at least” followed bya number is used herein to denote the start of a range beginning withthat number (which may be a range having an upper limit or no upperlimit, depending on the variable being defined). For example, “at least1” means 1 or more than 1. The term “at most” followed by a number isused herein to denote the end of a range ending with that number (whichmay be a range having 1 or 0 as its lower limit, or a range having nolower limit, depending upon the variable being defined). For example,“at most 4” means 4 or less than 4, and “at most 40%” means 40% or lessthan 40%. Terms of approximation (e.g., “about”, “substantially”,“approximately”, etc.) should be interpreted according to their ordinaryand customary meanings as used in the associated art unless indicatedotherwise. Absent a specific definition and absent ordinary andcustomary usage in the associated art, such terms should be interpretedto be ±10% of the base value.

When, in this document, a range is given as “(a first number) to (asecond number)” or “(a first number)−(a second number)”, this means arange whose lower limit is the first number and whose upper limit is thesecond number. For example, 25 to 100 should be interpreted to mean arange whose lower limit is 25 and whose upper limit is 100.Additionally, it should be noted that where a range is given, everypossible subrange or interval within that range is also specificallyintended unless the context indicates to the contrary. For example, ifthe specification indicates a range of 25 to 100 such range is alsointended to include subranges such as 26 -100, 27-100, etc., 25-99,25-98, etc., as well as any other possible combination of lower andupper values within the stated range, e.g., 33-47, 60-97, 41-45, 28-96,etc. Note that integer range values have been used in this paragraph forpurposes of illustration only and decimal and fractional values (e.g.,46.7−91.3) should also be understood to be intended as possible subrangeendpoints unless specifically excluded.

It should be noted that where reference is made herein to a processcomprising two or more defined steps, the defined steps can be carriedout in any order or simultaneously (except where context excludes thatpossibility), and the process can also include one or more other stepswhich are carried out before any of the defined steps, between two ofthe defined steps, or after all of the defined steps (except wherecontext excludes that possibility).

Still further, additional aspects of the instant invention may be foundin one or more appendices attached hereto and/or filed herewith, thedisclosures of which are incorporated herein by reference as if fullyset out at this point.

Thus, the invention is well adapted to carry out the objects and attainthe ends and advantages mentioned above as well as those inherenttherein. While the inventive concept has been described and illustratedherein by reference to certain illustrative embodiments in relation tothe drawings attached thereto, various changes and furthermodifications, apart from those shown or suggested herein, may be madetherein by those of ordinary skill in the art, without departing fromthe spirit of the inventive concept the scope of which is to bedetermined by the following claims.

What is claimed is:
 1. A process for selective recovery of lithium froma feed brine solution, said process comprising the steps of:concentrating said lithium in said brine solution by cyclically andsequentially flowing said brine solution through a continuouscountercurrent adsorption and desorption circuit to form an enhancedlithium product stream; and recovering said lithium from said enhancedlithium product stream.
 2. The process of claim 1 further comprising thesteps of: removing impurities from said brine solution to form apolished brine solution; concentrating said lithium in said polishedbrine solution by cyclically and sequentially flowing said polishedbrine solution through a continuous countercurrent adsorption anddesorption circuit to form an enhanced lithium product stream; andrecovering said lithium from said enhanced lithium product stream. 3.The process of claim 1 further comprising the step of obtaining saidbrine solution, said brine solution comprising lithium chloride.
 4. Theprocess of claim 3 further comprising the steps of: concentrating saidlithium chloride in said brine solution using said continuouscountercurrent adsorption and desorption circuit to form said enhancedlithium product stream, and then, selectively converting said lithiumchloride in said enhanced lithium product stream to lithium carbonate,lithium hydroxide, or both.
 5. The process of claim 1 wherein saidcontinuous countercurrent adsorption desorption circuit comprises aplurality of process zones, each of said process zones comprising anadsorbent bed or column having a lithium selective adsorbent.
 6. Theprocess of claim 5 wherein said lithium selective absorbent is a lithiumalumina intercalate prepared from hydrated alumina, a lithium aluminumlayered double hydroxide chloride, a layered double hydroxide modifiedactivated alumina, a layered double hydroxide imbibed ion exchange resinor copolymer or molecular sieve or zeolite, layered aluminate polymerblends, a lithium manganese oxide, a titanium oxide, an immobilizedcrown ether, or a combination thereof.
 7. The process of claim 5 whereinsaid plurality of process zones further comprises: a brine displacementzone positioned upstream with respect to fluid flow of a brine loadingzone; said brine loading zone positioned upstream with respect to fluidflow of and in fluid communication with an entrainment rejection zone;said entrainment rejection zone positioned upstream with respect tofluid flow of and in fluid communication with an elution zone; and saidelution zone in fluid communication with said brine displacement zone.8. The process of claim 7 further comprising the step of passing saidbrine solution through said loading zone for a predetermined amount ofcontact time
 9. The process of claim 1 further comprising the steps ofdewatering said enhanced lithium product stream using a membraneseparation.
 10. The process of claim 9 wherein said membrane separationcomprises reverse osmosis or nano-filtration.
 11. The process of claim 9further comprising the step of dewatering and concentrating saidenhanced lithium product stream to produce a high lithium concentration,enhanced lithium product stream and a recycle eluant solution.
 12. Theprocess of claim 11 further comprising the step of providing saidenhanced lithium product stream, said high lithium concentration,enhanced lithium product stream or both to a lithium solvent extractionand electrowinning process, a solvent extraction and membraneelectrolysis process, or a recovery process for production of highpurity lithium hydroxide and lithium carbonate for battery production.13. The process of claim 1 wherein said brine solution comprises anatural brine, a synthetic brine, or a combination thereof.
 14. Theprocess of claim 1 wherein said brine solution comprises a continentalbrine, a geothermal brine, an oil field brine, a brine from hard rocklithium mining, or a combination thereof.
 15. A continuouscountercurrent adsorption desorption circuit configured for theselective adsorption and recovery of lithium from a lithium-rich brinesolution, said circuit comprising: a plurality of process zones, each ofsaid process zones comprising a plurality of adsorbent beds or columnshaving a lithium selective adsorbent; wherein said plurality of processzones further comprises: a brine displacement zone positioned upstreamwith respect to fluid flow of a brine loading zone; said brine loadingzone positioned upstream with respect to said fluid flow of and in fluidcommunication with an entrainment rejection zone; said entrainmentrejection zone positioned upstream with respect to fluid flow of and influid communication with an elution zone; and said elution zone in fluidcommunication with said brine displacement zone.
 16. The circuit ofclaim 15 wherein said lithium-rich brine solution comprises a naturalbrine, a synthetic brine, or a combination thereof.
 17. The circuit ofclaim 15 wherein said lithium-rich brine solution comprises acontinental brine, a geothermal brine, an oil field brine, a brine fromhard rock lithium mining, or a combination thereof.
 18. The circuit ofclaim 15 wherein said lithium selective absorbent is a lithium aluminaintercalate prepared from hydrated alumina, a lithium aluminum layereddouble hydroxide chloride, a layered double hydroxide modified activatedalumina, a layered double hydroxide imbibed ion exchange resin orcopolymer or molecular sieve or zeolite, layered aluminate polymerblends, a lithium manganese oxide, a titanium oxide, an immobilizedcrown ether, or a combination thereof.
 19. The circuit of claim 15wherein said circuit further comprises a central multi-port valvesystem.
 20. A continuous adsorption and desorption process for recoveryof lithium from a brine solution, said process comprising the steps of:a) displacing a lithium-containing feed brine solution from a freshlyloaded adsorbent bed or column using a lithium product eluate andpassing a displacement liquor solution to a brine feed inlet of alithium adsorption zone; b) incorporating said displacement liquorsolution into said feed brine solution to form a combined liquor/feedbrine solution; c) passing said combined liquor/feed brine solutionthrough a lithium loading zone where lithium is adsorbed on one or moreloading adsorbent beds or columns and forming a lithium depleted brineraffinate; d) displacing an eluate solution from said loading adsorbentbeds with a portion of said lithium depleted brine raffinate from saidlithium loading zone and into an elution zone; e) flowing a fresh eluantsolution through said elution zone stripping a portion of lithiumadsorbed on said adsorbent beds or columns; and f) collecting a portionof said eluant having high lithium concentration as an enhanced lithiumproduct solution.